As investigators try to piece together why Aaron Alexis opened fire on the Navy Yard in Washington on Monday, published reports said the 34-year-old suffered from mental illness including Post Traumatic Stress Disorder.

The family of Alexis believed he suffered from anger management issues associated with Post Traumatic Stress Disorder, something he developed after helping with 9/11 rescue efforts.

Dr. Rachel Hoffman with Meridian Community Care said PTSD can happen to anyone who experiences an extremely stressful situation such as a fire, flood or criminal assault.

Living through those situations triggers a response in victims and a variety of symptoms can occur. Child psychiatrist Dr. Pradeep Mathur with Belmont Pines Hospital said those symptoms can include extreme anxiety to the point of panic, flashbacks and nightmares. People can become isolated or even feel too emotionally attached.

“They feel like they’re in that flight or fight response all the time. They feel really keyed up,” said Hoffman. “They have a lot of uncomfortable energy and they sort of feel like they’ll jump out of their skin.”

The victims and witnesses of the Naval Yard shooting now run the risk of developing PTSD.

“The biggest thing is counseling to help them with that,” said Mathur. “Not just for themselves but even for their families.”

Doctors say PTSD can occur immediately after the incident or it can appear months later but the condition can be treated.